“Wait until you see when (Mayweather) falls – how you all write him off after this and he becomes like Aldo,” McGregor told reporters at the UFC Performance Institute. “Aldo was him at one stage and he just becomes nothing.”

McGregor knocked out Aldo in just 13 seconds. It was one of the most iconic moments in the history of mixed martial arts. Not many believed McGregor’s power would be enough to thwart Aldo, who ruled over the featherweight division for a decade.

Against Mayweather, who sports a perfect 49-0 record and the distinction of being the most unhittable fighter in boxing history, McGregor attempts to do the impossible once again in his first-ever professional boxing match.

Not many believe he can win. But it’s not the first time McGregor has been doubted.

“I don’t know how many times they’ve labeled me a joke,” McGregor said. “‘He’s a joker. What weight is he moving; what weight is he hitting; what weight is this? He doesn’t stand a chance.’

“And then the poor guy that’s in there with me has to deal with it, and then he’s unconscious and it’s on to the next one. And then there’s more questions and more doubts. This will just continue until I call it a day.”

McGregor worked out for about an hour and a half, hitting the bags and putting on a show for the media assembled.

During his workout, UFC president Dana White tweeted out video footage of McGregor’s sparring session with former boxing world champion Paulie Malignaggi. The footage showed McGregor connecting with a vicious straight left, his signature shot, that seemed to wobble Malignaggi.

In a fight where some have suggested McGregor will struggle to land a single punch against Mayweather, the viral footage certainly adds a new dimension to the fight.

“I’m going to spark (Mayweather). I’m going to come forward and go at him,” McGregor said. “He’s saying he’s going to come at me. Let’s see who takes the first back step. That will be the first win or loss in the fight: Who takes a back step first?”

McGregor isn’t planning any back steps as he attempts once again to accomplish the impossible on Aug. 26 vs. Mayweather at T-Mobile Arena. He’s getting used to proving doubters wrong.

“I’m scheduling bouts with opponents, telling them what I’m going to do to them and how I’m going to do it. And then I’m doing it. And then the train just kind of rolls with it and it keeps picking up steam as the predictions keep coming true,” he said.

“I don’t know how many times I’ve shocked the world right now (but) I’m going to shock it once again.”